This invention relates to a method and apparatus for controlling data transfer between input and output devices and a direct digital controller.
Different from the prior art analogue adjusting meter, the direct digital controller (DDC) is a device for sequentially controlling a plurality of processes or the like directly by a digital operation circuit.
Since a DDC controls a plurality of input and output devices operating simultaneously, input and output signals processed thereby are complicated and are abundant in number. For this reason the construction of the various input and output devices is not only complicated but also expensive.
In the prior art DDC, each of registers for reading out or writing in is assigned with a particular designating code and the designation of register is performed by said particular code. Therefore decoders in the input and output circuit are required equal to the number of registers, which means that the input and output circuits become complicated and that in case of installing input and output registers the number of decoder circuits corresponding thereto is increased. This requires the change of the circuits for input and output devices and the provision of the input and output devices for respective apparatus.
In the prior art when transferring data to and from the DDC, each of the input and output devices is assigned with a particular designating code within the data being transferred. Therefore, decoders equal to the number of input and output devices are required.